Spurious signals can degrade the performance of phase locked loops and the performance of the systems in which the phase locked loops are used. If not accounted for, spurious signals impair the ability of a phase locked loop to acquire and maintain a phase-locked condition. The chance of false locking, that is, phase locking to an undesired spurious signal rather than a desired locking signal provided by a voltage controlled oscillator (VCO), also increases as the amplitudes of spurious signals increase relative to the amplitude of locking signal.